Gardasil 9 (human papillomavirus 9-valent vaccine, recombinant) is prescribed to help prevent genital warts and certain types of cancer. This vaccine can cause side effects ranging from mild to serious. Examples include dizziness and headache.

Gardasil 9 is approved for use in people ages 9 through 45 years. It helps prevent genital warts as well as certain precancers and cancers caused by particular strains of human papillomavirus (HPV). Specifically, it’s used to help prevent the following conditions:

In this article, we use the terms “female” and “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

The active ingredient in Gardasil 9 is recombinant 9-valent human papillomavirus. (“Recombinant” means genetically produced.) It is not a live vaccine. Gardasil 9 comes as a suspension, which is a type of liquid mixture. A healthcare professional injects the vaccine into a muscle of the upper arm.

Keep reading to learn about the common, mild, and serious side effects that Gardasil 9 can cause. For a general overview of the drug, including details about its uses, see this article.

Some people, but not everyone, may experience mild to serious side effects after a Gardasil 9 injection. Below are a few of the more common side effects of Gardasil 9 reported in studies:

  • injection site reaction (See the “Side effects explained” section below to learn more.)
  • headache
  • fever
  • fatigue (low energy)

The following sections include more side effects of Gardasil 9.

Mild side effects have been reported with Gardasil 9. These include:

  • nausea
  • dizziness
  • fatigue (low energy)
  • diarrhea
  • sore throat
  • muscle aches
  • pain in the upper belly
  • fever
  • headache
  • injection site reaction (See the “Side effects explained” section below to learn more.)

In most cases, these side effects should be temporary. And some may be managed easily. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop your Gardasil 9 vaccination series unless your doctor recommends it.

Gardasil 9 may cause mild side effects other than those listed above. See the vaccine’s prescribing information for details.

Serious side effects have been reported with Gardasil 9. These include:

If you develop serious side effects after injections of Gardasil 9, call your doctor right away. If the side effects seem life threatening or you think you have a medical emergency, immediately call 911. Or call your local emergency number.

Note: After the Food and Drug Administration (FDA) approves a vaccine, it and the Centers for Disease Control and Prevention (CDC) track the side effects. If you’d like to report a side effect you’ve had with Gardasil 9, visit the Vaccine Adverse Event Reporting System (VAERS) website.

Allergic reaction

Allergic reaction was a rare side effect reported in Gardasil 9’s studies.

For safety reasons, you should stay at the location where you’ve received the vaccine for 15 to 30 minutes. This will allow a doctor or pharmacist to monitor you for allergic reaction.

In some people, an allergic reaction may be due to the yeast component of the vaccine. If you’ve ever had a severe allergic reaction to yeast, you should not receive Gardasil 9.

In general, symptoms of an allergic reaction can be mild or serious. You can learn more about possible symptoms in this article.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. And they can determine whether you should receive any remaining Gardasil 9 doses.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911. Or call your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

Your doctor can confirm whether you’ve had a serious allergic reaction to Gardasil 9. If you have, they may advise you not to receive any further doses.

Get answers to some frequently asked questions about Gardasil 9’s side effects.

Can avoiding activities after a Gardasil 9 vaccine reduce side effects?

It depends. If you have side effects such as dizziness or fever after receiving a dose of Gardasil 9, rest and avoid strenuous activities. Otherwise, you can continue with your activities as usual.

If you’re unsure whether to avoid certain activities after a Gardasil 9 injection, ask your doctor or pharmacist.

How long will the side effects of Gardasil 9 last?

Most side effects after a Gardasil 9 dose will go away after 1 or 2 days. Swelling, bruising, or skin that is red or deepened in color may last 3 to 5 days.

If your side effects last longer or worsen, check with your doctor or pharmacist.

Can Gardasil 9 cause long-term side effects?

Gardasil 9 studies did not reveal any long-term side effects. But as with all vaccines, a very low possibility of a severe allergic reaction exists. And in extreme cases or if symptoms of a severe allergic reaction are untreated, serious harm or death could result.

Talk with your doctor or pharmacist if you have questions about these risks.

Learn more about some of the side effects Gardasil 9 may cause.

Injection site reaction

Injection site reaction was a common side effect reported in studies of Gardasil 9. This side effect may cause symptoms such as these at the site of injection:

  • swelling
  • red, purple, or discolored skin
  • pain or tenderness
  • a hard lump
  • bleeding
  • bruising
  • a blood blister
  • itching
  • warmth

Factors that can raise the risk of injection site reaction include:

  • positioning the arm incorrectly during injection
  • injecting vaccine that is cold
  • having a past sensitivity to vaccine ingredients

What might help

You can help minimize the likelihood of injection site reaction after Gardasil 9 doses. To do so, take these precautions:

  • Inform your doctor or pharmacist of any previous sensitivity or reaction to vaccines.
  • Remove your arm completely from long-sleeved clothing during the injection.
  • Make sure your clothing is not too tight above the injection site.
  • Allow your arm to hang loosely by your side when receiving the injection.
  • Avoid vigorous rubbing of the injection site after you receive a dose.

Vaccines stimulate the immune system. So despite taking precautions, you still could have a reaction at the injection site.

To relieve injection site reactions, use over-the-counter medications or home remedies. These include:

  • using acetaminophen for pain relief
  • applying a cool compress at the site

If you have the following symptoms lasting more than 24 hours, seek an urgent medical evaluation:

  • streaks down the arm that are red or deepened in color
  • swollen, hot lump at the injection site or under the arm
  • difficulty moving your arm

Fainting after vaccination

Fainting after vaccination was a side effect reported in studies of Gardasil 9. But it’s unclear how often this occurred. This side effect may cause symptoms such as:

  • skin that is pale or lightened in color
  • sweating
  • nausea
  • vomiting
  • loss of consciousness
  • muscle twitching or jerking
  • confusion
  • low heart rate
  • feeling dizzy or lightheaded

A vasovagal response usually causes fainting after receiving a vaccine. This happens when your body is overstimulated by certain triggers. (Some triggers are stress, fear, pain, or hypodermic needles used for injections.) When it’s overstimulated, you might faint from decreased blood flow to the brain.

What might help

To reduce the risk of fainting and injury, remain seated during a Gardasil 9 injection. If you’ve ever fainted from a vaccination, lie down during the injection. And remain seated or lying down for 15 minutes after.

Prior to getting vaccinated, eat 1 to 2 hours beforehand and drink plenty of water.

In most cases, fainting lasts only a few minutes before people recover. If you do faint, your doctor or pharmacist will have you stay at the location where you’ve received the vaccine until you’re feeling better.

Keeping track of side effects

After your Gardasil 9 vaccination, consider taking notes on any side effects you’re having. You can then share this information with your doctor.

Your side effect notes can include things such as:

  • how soon you had the side effect after receiving Gardasil 9
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Gardasil 9 affects you. They can then use this information to adjust your vaccination plan if needed.

Below is important information you should consider before receiving Gardasil 9.

Warnings

Gardasil 9 can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Gardasil 9 is a good vaccine option for you.

Talk with your doctor about your health history before you receive Gardasil 9. Be sure to tell them if any of the following factors apply to you:

  • history of fainting after a vaccination
  • allergy to yeast
  • past allergic reaction to Gardasil 9
  • receiving treatments or medications that weaken the immune system
  • taking other medications, over-the-counter drugs, herbs, vitamins, or nutritional supplements
  • pregnancy (The Centers for Disease Control and Prevention recommends avoiding Gardasil 9 vaccination until after pregnancy.)
  • breastfeeding
  • alcohol consumption

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.